The present invention relates generally to improvements in electric alarm clocks, and in particular to an improved tripping and cancelling mechanism for alarm clocks which produce electrical signals. The invention also relates to an associated switch for switching on and off an auxiliary device, such as a lamp, which can be incorporated into or attached to the clock.
In the case of alarm clocks which produce an electrical signal, it is normal practice to control the production of the signal by means of two switches which are arranged in series and close the signal generating circuit.
The first switch is operated by hand and, when closed, serves to set the alarm mechanism in readiness for the production of the signal. The signal can be cancelled by opening this switch.
The second switch is coupled to the hour wheel or alarm tripping wheel of the clock. It closes when the preset alarm time is reached, whereupon a dog carried by the hour wheel may drop into a recess in the alarm tripping wheel.
Thus, the circuit is arranged so that a signal is only produced when both the switches are closed.
In addition a third switch is provided for illuminating the bezel of the face of the clock when desired or to enable an auxiliary device such as a reading light to be switched on.
Because these switches are elaborate in design and liable to breakdown, and because a relatively large number of working steps and soldering operations are required to incorporate them in the clock it is desirable to reduce the number of switches required.
Accordingly, the present invention comprises an alarm clock which produces an electric signal and which operates in conjunction with an electric auxiliary device, wherein the circuit required to produce said signal and the circuit required to energize said auxiliary device are closed and opened by means of a single electrical contacting spring.
Thus, a single spring will suffice for all the three aforementioned switching functions (tripping the alarm, manually cancelling the alarm, switching the light on and off).